The Windows Installer is a Microsoft service that is responsible for installing softwares as well as uninstalling them.Microsoft Windows Installer service is a built-in feature in Windows 2000, Windows XP,Windows  2003 and Vista. With it, developers is able to reduce all cost to efficiently build and configure applications for Windows systems.
If the windows installer service is stopped or damaged you  will get an error message , “Windows Installer Error 1720 / 1722,” every time you try to install or uninstall a certain software. Normally the original MSI installation files will be cached in the 'C:winntInstaller' directory before installation is started. Improper caching of an MSI file is one of the main causes of the error also.

But  How to solve Windows Installer Error 1720?

First maybe you need to do is re-register the windows installer service and everything is fixed. So you might want to try this step first before proceeding to the ultimate solution of the problem.Click  start menu and click on “Run” (XP), or the start search box for Vista and type in “Msiexec /unregister“ .And do the same thing with this command “Msiexec /regserver“.

If the solution did not resolve your problem then you can go ahead and install the latest and stable version of windows installer.If the installation is unable to locate the required files, try to use the Windows' 'Search' feature to look for the files and provide the location to the installation process.

If the windows installer error 1720 remains, you may need to use a PC error Fixer or registry cleaner to scan your computer. Those tools are specifically designed to rid your computer's registry of the left over wreckage resulting from unsuccessful installations. It will clean out the problem behind unsuccessful installations by cleaning from your registry all of the unnecessary files and harmful programs that interfere with regular computer functions.  It is the one-stop solution to most of your computer malfunction problems and can rid you of those "installation error" messages, directly.

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